Sampling

• Random Sampling


  All members of the target population have an equal chance to be picked (Wheel, names in a hat)
• Strength of Random sampling

  No researcher bias
• Weakness of Random Sampling

  Difficult and time consuming

  May be unrepresentative
• Systematic Sampling


  Selection is done through ordered system - every Nth person
• Strength of Systematic Sampling

  Quick, easy and cheap
• Weakness of Systematic Sampling

  Chance of biased sample
• Stratified Sampling


  The sample represents the proportions of people in certain groups within the target population
• Strength of Stratified Sampling

  Avoids researcher bias

  Produces representative sample
• Weakness of Stratified Sampling

  Cannot always reflect peoples differences
• Opportunity Sample

  Selecting anyone who is willing and able to do the study
• Strength of Opportunity Sample

  Convenient and Cheap
• Weakness of Opportunity Sample

  Can be unrepresentative of the target population

  Possible researcher bias
• Volunteer sample


  Picked through chance of them joining - select themselves to take part
• Strength of Volunteer sample

  Easy - minimal research input
• Weakness of Volunteer sample

  Volunteer bias - may attract a certain type of person